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A simultaneous XMM-Newton and BeppoSAX observation of the archetypal broad line Seyfert 1 galaxy NGC 5548

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journal contribution
posted on 08.02.2016, 12:25 by Kenneth Alwyne Pounds, J. N. Reeves, K. L. Page, R. Edelson, G. Matt, G. C. Perola
We report the spectral analysis of a long XMM–Newton observation of the well-studied, moderate luminosity broad line Seyfert 1 galaxy NGC 5548. The source was at an historically average brightness and we find the hard (3–10 keV) spectrum can be well fitted by a power law of photon index Γ∼ 1.75, together with reflection. The only feature in the hard X-ray spectrum is a narrow emission line near 6.4 keV, with an equivalent width of ∼60 eV. The energy and strength of this line are consistent with fluorescence from ‘neutral’ iron distant from the central continuum source. We find no evidence for a broad Fe K line, with an upper limit well below previous reports, suggesting the inner accretion disc is now absent or highly ionized. The addition of simultaneous BeppoSAX data allows the analysis to be extended to 200 keV, yielding important constraints on the total reflection. Extrapolation of the hard X-ray power law down to 0.3 keV shows a clear ‘soft excess’ below ∼0.7 keV. After due allowance for the effects of a complex warm absorber, measured with the XMM–Newton RGS, we find that the soft excess is better described as a smooth upward curvature in the continuum flux below ∼2 keV. The soft excess can be modelled either by Comptonized thermal emission or by enhanced reflection from the surface of a highly ionized disc.

History

Citation

Monthly Notices of the Royal Astronomical Society, 2003, 341 (3), pp. 953-960

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society

Publisher

Royal Astronomical Society

issn

0035-8711

eissn

1365-2966

Acceptance date

28/01/2003

Copyright date

2003

Available date

08/02/2016

Publisher version

http://mnras.oxfordjournals.org/content/341/3/953.short

Language

en